*
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
*
- * $Id: thread.c,v 1.6 2003/09/05 17:43:40 momjian Exp $
+ * $Id: thread.c,v 1.7 2003/09/13 14:49:51 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
+#include <pthread.h>
+#include <sys/types.h>
+#include <pwd.h>
+
/*
* Threading sometimes requires specially-named versions of functions
* that return data in static buffers, like strerror_r() instead of
* strerror(). Other operating systems use pthread_setspecific()
* and pthread_getspecific() internally to allow standard library
- * functions to return static data to threaded applications.
+ * functions to return static data to threaded applications. And some
+ * operating systems have neither, meaning we have to do our own locking.
*
* Additional confusion exists because many operating systems that
* use pthread_setspecific/pthread_getspecific() also have *_r versions
* doesn't have strerror_r(), so we can't fall back to only using *_r
* functions for threaded programs.
*
- * The current setup is to assume either all standard functions are
- * thread-safe (NEED_REENTRANT_FUNC_NAMES=no), or the operating system
- * requires reentrant function names (NEED_REENTRANT_FUNC_NAMES=yes).
+ * The current setup is to try threading in this order:
+ *
+ * use non-*_r function names if they are all thread-safe
+ * (NEED_REENTRANT_FUNCS=no)
+ * use *_r functions if they exist (configure test)
+ * do our own locking and copying of non-threadsafe functions
+ *
* Compile and run src/tools/test_thread_funcs.c to see if your operating
- * system requires reentrant function names.
+ * system has thread-safe non-*_r functions.
*/
char *
pqStrerror(int errnum, char *strerrbuf, size_t buflen)
{
-#if defined(USE_THREADS) && defined(NEED_REENTRANT_FUNC_NAMES)
+#if defined(FRONTEND) && defined(USE_THREADS) && defined(NEED_REENTRANT_FUNCS) && defined(HAVE_STRERROR_R)
/* reentrant strerror_r is available */
/* some early standards had strerror_r returning char * */
strerror_r(errnum, strerrbuf, buflen);
- return (strerrbuf);
+ return strerrbuf;
+
#else
+
+#if defined(FRONTEND) && defined(USE_THREADS) && defined(NEED_REENTRANT_FUNCS) && !defined(HAVE_STRERROR_R)
+ static pthread_mutex_t strerror_lock = PTHREAD_MUTEX_INITIALIZER;
+ pthread_mutex_lock(&strerror_lock);
+#endif
+
/* no strerror_r() available, just use strerror */
- return strerror(errnum);
+ StrNCpy(strerrbuf, strerror(errnum), buflen);
+
+#if defined(FRONTEND) && defined(USE_THREADS) && defined(NEED_REENTRANT_FUNCS) && !defined(HAVE_STRERROR_R)
+ pthread_mutex_unlock(&strerror_lock);
+#endif
+
+ return strerrbuf;
#endif
}
pqGetpwuid(uid_t uid, struct passwd *resultbuf, char *buffer,
size_t buflen, struct passwd **result)
{
-#if defined(USE_THREADS) && defined(NEED_REENTRANT_FUNC_NAMES)
+#if defined(FRONTEND) && defined(USE_THREADS) && defined(NEED_REENTRANT_FUNCS) && defined(HAVE_GETPWUID_R)
/*
* Early POSIX draft of getpwuid_r() returns 'struct passwd *'.
* getpwuid_r(uid, resultbuf, buffer, buflen)
*/
/* POSIX version */
getpwuid_r(uid, resultbuf, buffer, buflen, result);
+
#else
+
+#if defined(FRONTEND) && defined(USE_THREADS) && defined(NEED_REENTRANT_FUNCS) && !defined(HAVE_GETPWUID_R)
+ static pthread_mutex_t getpwuid_lock = PTHREAD_MUTEX_INITIALIZER;
+ pthread_mutex_lock(&getpwuid_lock);
+#endif
+
/* no getpwuid_r() available, just use getpwuid() */
*result = getpwuid(uid);
+
+#if defined(FRONTEND) && defined(USE_THREADS) && defined(NEED_REENTRANT_FUNCS) && !defined(HAVE_GETPWUID_R)
+
+ /* Use 'buffer' memory for storage of strings used by struct passwd */
+ if (*result &&
+ strlen((*result)->pw_name) + 1 +
+ strlen((*result)->pw_passwd) + 1 +
+ strlen((*result)->pw_gecos) + 1 +
+ /* skip class if it exists */
+ strlen((*result)->pw_dir) + 1 +
+ strlen((*result)->pw_shell) + 1 <= buflen)
+ {
+ memcpy(resultbuf, *result, sizeof(struct passwd));
+ strcpy(buffer, (*result)->pw_name);
+ resultbuf->pw_name = buffer;
+ buffer += strlen(resultbuf->pw_name) + 1;
+ strcpy(buffer, (*result)->pw_passwd);
+ resultbuf->pw_passwd = buffer;
+ buffer += strlen(resultbuf->pw_passwd) + 1;
+ strcpy(buffer, (*result)->pw_gecos);
+ resultbuf->pw_gecos = buffer;
+ buffer += strlen(resultbuf->pw_gecos) + 1;
+ strcpy(buffer, (*result)->pw_dir);
+ resultbuf->pw_dir = buffer;
+ buffer += strlen(resultbuf->pw_dir) + 1;
+ strcpy(buffer, (*result)->pw_shell);
+ resultbuf->pw_shell = buffer;
+ buffer += strlen(resultbuf->pw_shell) + 1;
+
+ *result = resultbuf;
+ }
+ else
+ *result = NULL;
+
+ pthread_mutex_unlock(&getpwuid_lock);
+#endif
#endif
return (*result == NULL) ? -1 : 0;
}
*/
int
pqGethostbyname(const char *name,
- struct hostent *resbuf,
- char *buf, size_t buflen,
+ struct hostent *resultbuf,
+ char *buffer, size_t buflen,
struct hostent **result,
int *herrno)
{
-#if defined(USE_THREADS) && defined(NEED_REENTRANT_FUNC_NAMES)
+#if defined(FRONTEND) && defined(USE_THREADS) && defined(NEED_REENTRANT_FUNCS) && defined(HAVE_GETHOSTBYNAME_R)
/*
* broken (well early POSIX draft) gethostbyname_r() which returns
* 'struct hostent *'
*/
- *result = gethostbyname_r(name, resbuf, buf, buflen, herrno);
+ *result = gethostbyname_r(name, resbuf, buffer, buflen, herrno);
return (*result == NULL) ? -1 : 0;
+
#else
+
+#if defined(FRONTEND) && defined(USE_THREADS) && defined(NEED_REENTRANT_FUNCS) && !defined(HAVE_GETHOSTBYNAME_R)
+ static pthread_mutex_t gethostbyname_lock = PTHREAD_MUTEX_INITIALIZER;
+ pthread_mutex_lock(&gethostbyname_lock);
+#endif
+
/* no gethostbyname_r(), just use gethostbyname() */
*result = gethostbyname(name);
+
+#if defined(FRONTEND) && defined(USE_THREADS) && defined(NEED_REENTRANT_FUNCS) && !defined(HAVE_GETHOSTBYNAME_R)
+
+ /*
+ * Use 'buffer' memory for storage of structures used by struct hostent.
+ * The layout is:
+ *
+ * addr pointers
+ * alias pointers
+ * addr structures
+ * alias structures
+ * name
+ */
+ if (*result)
+ {
+ int i, pointers = 2 /* for nulls */, len = 0;
+ char **pbuffer;
+
+ for (i = 0; (*result)->h_addr_list[i]; i++, pointers++)
+ len += (*result)->h_length;
+ for (i = 0; (*result)->h_aliases[i]; i++, pointers++)
+ len += (*result)->h_length;
+
+ if (MAXALIGN(len) + pointers * sizeof(char *) + strlen((*result)->h_name) + 1 <= buflen)
+ {
+ memcpy(resultbuf, *result, sizeof(struct hostent));
+
+ pbuffer = (char **)buffer;
+ resultbuf->h_addr_list = pbuffer;
+ buffer += pointers * sizeof(char *);
+
+ for (i = 0; (*result)->h_addr_list[i]; i++, pbuffer++)
+ {
+ memcpy(buffer, (*result)->h_addr_list[i], (*result)->h_length);
+ resultbuf->h_addr_list[i] = buffer;
+ buffer += (*result)->h_length;
+ }
+ resultbuf->h_addr_list[i] = NULL;
+ pbuffer++;
+
+ resultbuf->h_aliases = pbuffer;
+
+ for (i = 0; (*result)->h_aliases[i]; i++, pbuffer++)
+ {
+ memcpy(buffer, (*result)->h_aliases[i], (*result)->h_length);
+ resultbuf->h_aliases[i] = buffer;
+ buffer += (*result)->h_length;
+ }
+ resultbuf->h_aliases[i] = NULL;
+ pbuffer++;
+
+ /* Place at end for cleaner alignment */
+ strcpy(buffer, (*result)->h_name);
+ resultbuf->h_name = buffer;
+ buffer += strlen(resultbuf->h_name) + 1;
+
+ *result = resultbuf;
+ }
+ else
+ *result = NULL;
+ }
+#endif
+
+ if (*result != NULL)
+ *herrno = h_errno;
+
+#if defined(FRONTEND) && defined(USE_THREADS) && defined(NEED_REENTRANT_FUNCS) && !defined(HAVE_GETHOSTBYNAME_R)
+ pthread_mutex_unlock(&gethostbyname_lock);
+#endif
+
if (*result != NULL)
return 0;
else
- {
- *herrno = h_errno;
return -1;
- }
#endif
}
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